"Surgeons use a variety of techniques to grow skin for tissue expansion procedures designed to grow skin in one region of the body so that it can be auto-grafted on to another site (sometimes used for burn victims)," said Guy German, Assistant Professor at the Binghamton University in New York, US.
This procedure stretches the skin, typically, by inflating a balloon with air or silicone under the surface. Skin grows more in regions where it is stretched -- during pregnancy, for instance -- but stretch it too much and the tissue might break.
"Our predictive technique could be employed in this field as a method of predicting the limit to which the skin could be stretched," German added.
The outermost layer of skin, the stratum corneum, regulates water loss from the body and protects underlying living tissue from germs and the environment, in general. It is pretty tough, protecting the body from extreme temperatures, rough surfaces, and most paper edges.
In the study, assuming that the skin is smooth and without major cracks, the researchers looked how the toughness of skin varied significantly in relation to its water content. They found dry skin is brittle and easier to break than hydrated skin.
Then, they used advanced imaging to track skin deformation and stretching which, combined with the structure of the skin itself, correlates to where cracks in skin begin.
This can help scientists and doctors predict where fractures may occur in the future, the study said.
They also found that cracks in the skin are not straight; instead they follow topographical ridges of skin, which have triangular patterns.
In addition, the team proved that most fractures propagate along cell-cell junctions rather than breaking the cells themselves. This does not always happen, but it suggests that cell junctions are structurally the weakest points of the skin, they said.
The results could help create new topical medical creams, soaps and cosmetic products. It may also be used in more extreme cases.
This work also sets the stage for a variety of future studies assessing changes in skin composition, environmental pH, or bacterial colonisation on skin's toughness, German noted, in the paper published in the journal Acta Biomaterialia.
